Most forest-dwelling members of the genus Camponotus excavate nests in wood, from which they derive their common name "carpenter ants". Three native species of the northeastern United States differ slightly, but significantly in their nesting habits. Although all prefer to excavate timber in some stage of decay, Camponotus herculeanus often makes tunnels in the soil; C. noveboracensis nests in very rotten wood and stumps; and C. pennyslvanicus nests both in rotten wood and standing trees. It is this latter species that may become a household pest, damaging building timbers and telephone poles. Many different kinds of trees are attacked, although preference is shown for soft woods such as balsam fir, white pine and cedar. This ant species has a wide range, occurring in the eastern United States and southern Canada as far as the hundredth meridian and south to the eastern Gulf States.
Control of these ants has been achieved by spraying the entrance of the nest with insecticides, such as emulsions of DDT or chlordane. Contact dusts, e.g., sodium floride have also been tried, and fair control was achieved with the use of 5% chlordane or 1% dieldrin. The use of wood preservatives such as coal tar creosote has also been employed, but the effectiveness of chemical poisons has proven to be only temporary unless the source of moisture that the ants require in the wood is eliminated. The wood eventually becomes susceptible to new attack. The problem usually lies in the timely detection of the nests before the damage has reached an advanced stage. The usual control is to put chlorinated hydrocarbon powder in likely foraging areas in the hope that the ants will carry it into the nest, but this is not a reliable method. The use of radioactive tracers to locate the nests has been suggested, which method carries with it obvious limitations for general application.
It has also been common practice to exterminate insects such as Camponotus by the use of gaseous poisons or by chopping down the damaged trees, methods hardly useful for controlling the ants in houses.
Some research has been done on the properties of Mirex, (dodecachlorooctahydro-1,3,4-metheno-1H-cyclobuta(cd)pentalene) a slow acting stomach poison, as a suitable toxicant. Echols discusses its use in the control of the Texas leaf-cutting ant Atta texana in Journal of Economic Entomology 39:1336- 1338. In view of the extensive control program on the imported fire ant Solenopsis invicta in the southern States of America, in which Mirex is used, its mode of action is being investigated by the U.S.D.A. Much of this work remains unpublished, although the initial field studies with baits (Bartlett and Lofgren, Journal of Economic Entomology 54:70- 73); and evaluations of baits and feeding tests with the fire ant (Lofgren et al., Journal of Economic Entomology 55:405- 407 and Stringer et al., Journal of Economic Entomology 57:941- 945) have been published.
A bait that contains a poison that kills too rapidly cannot be circulated throughout the whole colony by trophallaxis before the donors are too seriously affected to continue effectively to distribute the poison. The queen may be missed altogether, and the colony will thus survive and soon replenish its numbers. The toxicant also has to act effectively at low concentrations, so that despite dilution through food exchange among large numbers of ants, and despite attenuation through mixing with food collected from other natural sources, the poison will still be effective in eliminating the entire colony.
Mirex (C.sub.10 CL.sub.12) is a fully chlorinated closed 10-carbon structure described in the Bulletin of the Entomology Society of America, 1969 15:95. Mirex is a white crystalline solid, odorless, and partially soluble in some organic solvents. MIrex is a slow acting toxicant, which is an important characteristic when used to control such insects as carpenter ants and other insects having a life style such that some members of the colony do not gather food directly but instead receive food from donors that forage.
In the past, Mirex used as an insecticide was formulated in an oil-based solid bait since it is nearly completely insoluble in water. Some insects, e.g., Camponotus, do not feed significantly on oils, and demand food in liquid form in order to be taken up in quantity by the ants.